Lubricatng composition and method for treating metal-mold interface in continuous casting operation

ABSTRACT

A lubricating composition is prepared suitable for lubricating the interface of liquid metal and mold during the continuous casting of metals. This lubricating composition contains both the dimer and trimer of an unsaturated fatty acid, a glyceride oil, e.g., triglyceride, as a solubilizing agent, and a mineral lubricating oil having a low-carbon residue and low-aromatic carbon content which can be prepared by a two-stage catalytic hydrogenation process.

O Unlted States Patent 51 3,640,860 Miller 1 Feb. 8, 1972 [54]LUBRICATNG COMPOSITION AND 3,223,635 12/1965 Dwyer et al.... .....252/56METHOD FQR TREATING METAL. 3,269,939 8/1966 Marechal.... 208/143 MOLDINTERFACE IN CONTINUOUS 3:33:22 2232332321;;..........................:::$37 Z CASTING OPERATION [72]Inventor: Virgil A. Miller, Park Forest, Ill. 5; [73] Assignee: AtlanticRichfield Company, New York, Attorney--McLean, Morton and Boustead 57ABSTRACT [22] Filed: June 2, 1969 1 A lubricating composition isprepared suitable for lubricating 1 PP 829,715 the interface of liquidmetal and mold during the continuous casting of metals. This lubricatingcomposition contains both [52] U S Cl the dimer and trimer of anunsaturated fatty acid, a glyceride S oil, e.g., triglyceride, as asolubilizing agent, and a mineral 1] lubricating oil having a low-carbonresidue and low-aromatic [58] Field of Search l 64/713,208/143; 252/56carbon content which can be prepared by a two stage caudytic [56 R ihydrogenation process.

] e erences Cited 16 Claims, No Drawings UNITED STATES PATENTS 2,837,7916/1958 Tessmann ..l64/73 LUBRICA'ING COMPOSITION AND METHOD FOR TREATINGMETAL-MOLD INTERFACE IN CONTINUOUS CASTING OPERATION This invention isconcerned with a lubricating composition suitable for use in thecontinuous casting of metals. More specifically, this invention isconcerned with a composition useful for lubricating the metal-moldinterface during the continuous casting of metals, which compositioncontains both dimer and trimer of an unsaturated fatty acid, a glycerideoil, especially a triglyceride, as a solubilizing agent, and a minerallubricating oil component low in carbon residue and aromatic carboncontent. The mineral lubricating oil can be made by a two-statecatalytic hydrogenation process.

In the continuous casting of metals, molten metal is cast directly andcontinuously into billets and slabs without the necessity for the usualpouring into ingots, cooling, reheating and rolling normally required inother processes. The machinery employed in the continuous castingprocess may be of a number of designs but all contain certain basicelements. These are, in the order in which they are employed in theoperation, the ladle, the tundish, the mold, where primary cooling takesplace, a secondary cooling section, withdrawal rolls and cutoffequipment. In atypical casting operation molten metal, e.g., steel ispoured from the ladle into the tundish. From the tundish the liquidmetal flows in a continuous, uniform stream into the mold, which isequipped with a cooling system employing, for example, water as thecoolant. It is in this mold that partial solidification of the steelfirst takes place. Normally a tube or billet of metal is formedconsisting of a cooled, solid outer layer of metal surrounding a molteninner core of metal. This billet passes continuously from the mold,through withdrawal rollers and is further cooled, for example byspraying with water prior to passing through the cutoff equipment wherethe billet is cut by torches or by hydraulic knives into the desiredlengths.

One of the most significant problems which has been encountered in thecontinuous casting of metals particularly steel, is that of providingsatisfactory lubrication at the moldliquid metal interface. Thelubricant employed must, first of all, prevent welding of the steel tothe mold surface. Further, the lubricant should be consumed incombination when it contacts the high-temperature liquid metal (e.g.,about 2,800 F. for molten steel) with little or no residue left. Residuefrom the combustion of the lubricant may become entrained in the steeland result in blow out. Finally, as the lubricant is consumed, thereshould be a minimum of smoke since smoke prevents visual observation ofthe steel-mold interface which is necessary to proper control of thelubricant flow rate. The smoke is also objectionable to the operatingpersonnel.

Various compositions can be employed as lubricants for continuous metalcasting processes. One such lubricant contains a dimer of an unsaturatedfatty acid and a mineral lubricating oil of low carbon residue and lowaromatic carbon content.

In formulating this product it is desired to employ the dimer acid inits less expensive commercially available form in which the dimer ismixed with trimer of the unsaturated fatty acid. Unfortunately the useof the mixed dimer-trimer acids in the base mineral oil isunsatisfactory since insolubles appear in the product.

Now in accordance with the present invention, it has been found that theprovision of a glyceride oil, especially triglyceride oil, in themineral oil-dimer-trimer acid mixture overcomes the foregoing describedinsolubles problem, and at the same time a product is formed whichserves as an effective lubricant at the interface formed between themetal and the mold during the continuous casting of metals without theproduction of excessive smoke or residue. The lubricating composition ofthis invention thus comprises a major amount of mineral oil oflubricating viscosity having a low carbon residue and a low aromaticcarbon content, about 2 to 15, preferably about 3 to 10, weight percentof total dimer and trimer of an unsaturated fatty acid of about topreferably about 18 carbon atoms, sufficient trimer acid being presentto give insolubles in the mixed product, and glyceride oil, especially atriglyceride oil, in amount sufficient to solubilize the trimericunsaturated acid in the mineral oil. This invention thus relates to thesolubilization of a low-cost mixture, such as about 5 percent, of dimerand trimer acids in highly refined mineral oil by using an amount of aglyceride oil such as triglyceride oil, sufficient to solubilize themixture of dimer and trimer acids in the mineral oil. The glyceride oilor triglyceride oil is of at least 70 to 150 Iodine Number, preferablyless than about lodine Number, e.g., peanut oil.

The amount of trimer often present in the dimer-trimer acid component isa minor proportion of these acids and usually at least about 5 or evenat least about 10 weight percent of the total dimer and trimer acids.Sufficient glyceride oil or triglyceride is added to the product tosolubilize essentially all of the trimer acid. The amount of glycerideoil or triglyceride oil employed is often at least about 10 or even atleast about 20 weight percent of the composition and usually does notexceed about 30 weight percent. Various glyceride oils can be employed,such as soybean oil, peanut oil, their hydrogenated forms, etc. Theunsaturated fatty acids useful in forming the dimer and trimer acidsinclude, for instance, oleic acid, linoleic acid, ricinoleic acid, etc.

The mineral oil employed in my compositions is of lubricating viscosityand has a carbon residue below about 0.1, or even below about 0.05,Ramsbottom (ASTM D 524), and less than about 1 percent aromatic carbonatoms (carbon-type analysis) preferably essentially none. Although themineral oil can be derived from various crudes, there is a preference touse a mixed base oil rather than a naphthenic oil as the source of thelubricating oil component of our product. Mixed base crudes, andparaffinic crudes as well, can more readily yield predominantlyparaffinic lubricating oil fractions, and it is preferred that the oilcomponent of the compositions have at least about 60 percent paraffiniccarbon atoms.

The viscosity of the lubricating oil component of the compositions ofthis invention is such that the final formulation is fluid and readilyhandled as by pumping. Generally, the lubricating oil component, whichcan if desired be a mixture of oils, has a viscosity of at least aboutS.U.S. at 100 F. and often the viscosity does not exceed about 4,000S.U.S. at 100 F. The choice of oil can depend on the type of metal beingcast or the quality desired in the cast product. Thus with forging gradesteel the oil can with advantage have a flashpoint of at least about 500F. while with lower grade products, such as nonforging steel, lowerflashpoint oils of the order of at least about 280 F., preferably atleast about 290 F., can be employed with acceptable results.

The mineral oil employed in the present invention can be prepared byhydrogenating a distillate mineral lubricating oil feedstock in a dualstage catalytic system. In the first stage of the process the raw oil iscontacted with hydrogen at elevated temperature in the presence of asulfur-resistant hydrogenation catalyst. The hydrogenated oil from thefirst stage is then subjected to a second hydrogenation operation whichinvolves contact with hydrogen in the presence of a platinum groupmetal-promoted hydrogenation catalyst, usually under less severereaction conditions than used in the first hydrogenation stage, toproduce the high-quality mineral oil.

This process has been found to be particularly effective in providingmineral oils of high quality and in high yields, e.g., greater thanabout 90 percent. The oil feedstocks often have a viscosity in the rangeof about 50 to 7,500 S.U.S. at 100 F. lf the oils contain wax, and aproduct of low pour point is desired, the oils are dewaxed, preferablyprior to the first hydrogenation operation, although the dewaxing canfollow the first hydrogenation stage. Dewaxing can be carried out, forexample, by using a solvent such as methylethyl ketone and toluene toobtain an oil with a pour point (ASTM D 97) below about 25 F. The pourpoint necessary after dewaxing is determined by that required in thefinished oil.

The treatment in the first hydrogenation stage can be conducted attemperatures of about 600 to 750 F. Other suitable reaction conditionsinclude pressures of about 1,500 to 5,000 p.s.i.g., weight hourly spacevelocities (WHSV) of about 0.1 to l, and a hydrogen rate of about 1,000to 5,000 s.c.f./B. Preferred operating conditions are temperatures ofabout 600 to 700 F., about 1,500 to 3,000 p.s.i.g. pressure, a WHSV ofabout 0.2 to 0.5, and hydrogen flow rate of about 1,000 to 3,000s.c.f./B.

The hydrogenated oil from the first hydrorefining stage can then besubjected to hydrogenation over a platinum metal catalyst attemperatures of about 450 to 700 F. Other suitable reaction conditionsinclude pressures of about 1,000 to 5,000 p.s.i.g., WHSV of about 0.1 to1, and a hydrogen feed rate of about 500 to 5,000 s.c.f./B. To provideless severe reaction conditions in the second hydrogenation stage theaverage temperature is often at least about 50 F., preferably at leastabout 75 F., less than that of the first hydrogenation stage. Thepreferred range of conditions for the second stage are temperatures ofabout 525 to 650 F., pressures of about 1,000 to 3,000 p.s.i.g., WHSV ofabout 0.25 to 0.5, and hydrogen flow rates of about 500 to 3,000s.c.f./B.

The catalyst of the first hydrogenation operation can be of any of thesulfur-resistant, nonprecious metal hydrogenation catalysts, some ofwhich are conventionally employed in the hydrogenation of heavypetroleum oils. Examples of suitable catalytic ingredients are tin,vanadium, members of Group VlB in the Periodic Table, i.e., chromium,molybdenum and tungsten, and metals of the iron group, i.e., iron,cobalt and nickel. These metals are present in catalytically effectiveamounts, for instance, about 2 to 30 weight percent, and may be presentin the form of oxides, sulfides, or other form. Mixtures of thesematerials can be employed, for example, mixtures or compounds of theiron group, metal oxides or sulfides with the oxides or sulfides ofGroup VlB constitute very satisfactory catalysts. Examples of suchmixtures or compounds are nickel molybdate, tungstate, or chromate (orthiomolybdate, thiotungstate, thiochromate) or mixtures of nickel orcobalt oxides with molybdenum, tungsten or chromium oxides. As the artis aware these catalytic ingredients are generally employed whiledisposed on a suitable carrier of the solid oxide refractory type, e.g.,a predominately calcined or activated alumina. Commonly employedcatalysts have about 1 to percent of an iron group metal and 5 to 25percent of a Group VlB metal (calcined as the oxide). Advantageously,the catalyst is cobalt molybdate or nickel molybdate supported onalumina. Such preferred catalysts can be prepared by the methoddescribed in US. Pat. No. 2,938,002.

As aforementioned, the catalyst of the second hydrogenation operation isa platinum group metal-promoted catalyst. This catalyst is to bedistinguished from the catalysts of the first hydrogenation in that itis not normally considered to be sulfur-resistant. The catalyst includescatalytically effective amounts of the platinum group metals of GroupVlll, for instance platinum, palladium, rhodium or iridium, which arepresent in catalytically effective amounts, generally in the range ofabout 0.01 to 2 weight percent, preferably about 0.1 to 1 weightpercent. The platinum group metal may be present in the metallic form oras a sulfide, oxide or other combined form. The metal may interact withother constituents of the catalyst but if during use the platinum groupmetal is present in metallic form, then it is preferred that it be sofinely divided that it is not detectable by X-ray defraction means,i.e., that it exists as crystallites of less than about 50A. size. Ofthe platinum group metals, platinum is preferred. If desired, thecatalysts of the first and second hydrogenations can be hydrogen purgedor prereduced prior to use by heating in the presence of hydrogen,generally at temperatures of about 300 to 600" l". for purging or atabout 600 to 800 F. for prercduction.

Although various solid ref ractory-typc carriers known in the art may beutilized as a support for the platinum group metal, the preferredsupport is composed predominately of alumina of the activated orcalcined type. The alumina base is usually the major component of thecatalyst generally constituting at least about 75 weight percent on thebasis of the catalyst and preferably at least about to 99.8 percent. Thealumina catalyst base can be an activated or gamma-family alumina whichcan be derived from alumina monohydrate, alumina trihydrate, amorphoushydrous alumina or their mixtures. A catalyst base precursor which canbe used is a mixture predominating in, or containing a major proportionof, for instance about 65 to weight percent, of one or more of thealumina trihydrates, bayerite l, nordstrandite or gibbsonite, and about5 to 35 weight percent of alumina monohydrate (boehmite), amorphoushydrous alumina or their mixtures. The alumina base can contain smallamounts of other solid oxides such as silica, magnesia, natural oractivated clays (such as kaolinite, montmorillonite, halloysite, etc.),titania, zirconia, etc., or their mixture.

Following either of the hydrogenation operations the hydrogenated oilsin each case can be distilled or topped to remove any hydrocracked orother light materials that may have been formed. The removal of lightproducts increases the flashpoint of the oil. The degree of toppingdesired will depend on the particular lubricating oil fraction beinghydrogenated, the particular hydrogenation conditions employed and theflashpoint desired for the product. Thus, the amount of topped overheadthat may be taken off in the topping or distillation step after eitherhydrogenation operation may often vary from about 0 to 50 percent with 0to 10 percent being preferred.

In order to obtain effective lubrication during the continuous castingof metal and to prevent the metal from welding to the mold, a continuousfilm of lubricant is provided to the steel-mold interface. Typically, inmachinery now being used for continuous casting, a pump is providedwhich regulates the amount of lubricant present. The amount of lubricantprovided as well as the effectiveness of its distribution over the moldsurface is of importance. Too little lubricant in a particular spot mayresult in welding; too much lubricant causes sputtering which occurswhen excessive lubricant in the steel-mold interface suddenly andviolently vaporizes. Liquid steel blown from the mold during theeruption is a hazard to operating personnel. Effective lubricantdistribution in machines now in use is provided often by small slits ororifices in the side of the mold. Additionally, it has been foundeffective to have the lubricant pumped into reservoirs so located thatthe lubricant spills over out of the reservoirs evenly onto the moldwalls. The lubricating process of the present invention, employing thelubricating compositions which have been described may be carried outusing the various procedures and equipment known in the art forsupplying lubricant to the continuous casting mold. I

The following description is typical of the procedures which can beemployed in the process of the present invention. Steel is heated in anelectric furnace and transferred to a ladle. The ladle is placed in arack over a T-shaped tundish. A valve in bottom of ladle is controlledby the operator who observes the liquid steel level in tundish. Thetundish contains several holes through which steel flows to castingchutes. Each hole is equipped with a valve which is opened and closed bythe operator.

Beneath the tundish is positioned a block containing the castingpositions, each consisting of a cylindrical block equipped with a watercooling system. The cylindrical blocks are oscillated up and down duringthe pour. In the center of the cylindrical block is a square hole inwhich the copper casting chute or mold is placed. The chute is tightlysealed to the block and cooling water is circulated around it. As thecylindrical block oscillates up and down, the chute also oscillates.

The pour is started by filling the tundish with steel from the ladle.Steel flows out of the tundish in a rod shape, and falls 21 shortdistance through air before entering the casting chute. Before startingthe pour, a pyramid-shaped block is inserted in the lower end of thecasting chute. Steel freezes to this block, and the weight of steeleventually forces the block out of the casting chute. The block isfastened to a guiding chain and this device is used to thread the formedbillet through guideposts on a lower horizontal ramp. The weight ofliquid steel being continuously added at top of chute forces partiallysolidified steel out the bottom of chute. The cooling which takes placein the chute forms a solid outer layer around inner core of the liquidsteel. On leaving chute, the billet is bent from the vertical to thehorizontal position. The continuous billet is passed through a waterspray zone and cut into lengths suitable for loading.

In one machine employed, lubricant is pumped from central lube systemthrough tubing to the top of the casting chute. Lubrication inlets wereprovided on facing sides of the chute. In another machine, lubricant ispumped into four reservoirs and the lubricant overflowed evenly tolubricate the mold. One reservoir was associated with each wall of themold. Lubricant flowed down the sides of the chute, and burst intoflames when the steel was contacted. Some of lubricant danced over theliquid steel surface (2,800 F.) like water on a hot pancake griddle.Eventually a dancing ball of lubricant struck and wet the cooler coopermold. The lubricant was completely consumed in a single pass through themachine while the wetting action provided lubrication.

The preparation of a petroleum lubricating oil which is useful in thepresent invention is illustrated by the following example.

EXAMPLE A The starting material is a raw lubricating oil distillatefraction obtained by vacuum distillation of a Gulf Coast, naphthenicbase, reduced crude oil, the raw distillate having a viscosity of 1,000S.U.S. at 100 F. and a pour point of about 5 F. This oil is hydrogenatedat 2,500 p.s.i.g. hydrogen partial pressure, 680 F., 0.25 weight hourlyspace velocity, and a hydrogen rate of 2,200 s.c.f. of hydrogen perbarrel of oil over a cobalt molybdate on alumina catalyst containing2.7% C00 and l 1.9% M00 The hydrogenated product is flashed to removehydrogen and stripped to remove essentially all materials lighter thanlubricating oil. The stripped product is dried and then subjected to asecond hydrogenation operation at a pressure of 2,500 p.s.i.g. hydrogenpartial pressure, a temperature of 575 F., a weight hourly spacevelocity of 0.25 and a hydrogen rate of 2,500 s.c.f. of hydrogen perbarrel of feed over a platinum on alumina catalyst containing 0.6percent platinum. This material is then flashed to remove hydrogen andthe oil stripped to remove materials boiling below the desired product.

The properties of three products made by dual hydrogenation are listedin Table I. The feedstocks which were hydrogenated to give oils 1 and 2of Table I were derived from naphthenic base crude oils, oil 2 being atypical product made by Example I above. The feedstock which gave oil 1would typically have a viscosity of about 140 S.U.S. at 100 F. Afeedstock which can be used to product oil 3 at Table I can be derivedfrom a mixed base crude oil and can be a dewaxed raffinate from thephenol treatment of the raw distillate, the dewaxed product having aviscosity of about 230 S.U.S. at 100 F.

In addition to the essential dimer and trimer unsaturated fatty acidsand the glyceride or triglyceride oil, the mineral oil of lubricatingviscosity may contain additives for improving pour point and viscosityindex such as methacrylate ester polymers. These methacrylate esterpolymers include a series of commercially available polymers known asthe acryloids some of which are described in US. Pat. No. 2,710,842.

Molecular weight 333 416 487 Viscosity-gravity constant 0.825 0.8280.800

Specific dispersion 100.0 101. 8 100. 1

Carbon residue, Ramsbottom (carbon type).. 0. 01 0.05 0. 01 Hydrocarbonanalysis, percent:

Aromatic carbons 0 0 0 Naphthenic carbons. 58 57 31 Paraflinic carbons42 43 69 saturates 99. 9 92. 0

The following example is illustrative of this invention:

EXAMPLE The following formulation is typical of the lubricatingcompositions of the present invention. In this composition there wasemployed a mineral oil of lubricating viscosity prepared as in Example Ahaving a carbon residue below about 0.1 percent (Ramsbottom) and anaromatic carbon contact less than about 1 percent and designated MineralOil A.

Table II Composition A Mineral Oil A 74.0% Soybean Oil 20.0% VersadymeNo. 228' 5.0% Acryloid I50 [0% '1 Versadyme No. 228 obtained fromGeneral Mills is a polymerized unsaturated vegetable fatty acid formedfrom primarily C, unsaturated acids, and has the followingcharacteristics:

Acid Value 19! (188-195) Saponification Value l9) -20l) monomer 3 dimer76 trimer 2l 2 Acryloid ISO is a 40% concentrate in mineral oil of amethacrylate polymer in which the ester groups are derived from amixture of alcohols in the C to C range.

Product A was evaluated in a continuous steel (nonforging) castingoperation. The mold size was 4%X4V4 inches. In testing, Product A wasapplied to the mold by machine at the rate of 0.035 gal/ton of steel, aswell as applied by hand spraying. The results of the tests were asfollows:

Travel Test Pass time-the application product gave satisfactorylubrication at steel-mold inter face; l5 seconds is borderline; 20seconds is a solid pass.

' Measure of the ability of the lubricant to travel around thesteel-mold interface.

A small volume of Product A, one-half pint, provided adequatelubricating for casting 12 tons of steel (e.g., twothirds oz./ton or0.0l5 gaL/ton).

It is claimed:

1. A lubricating composition suitable for use in the continuous castingof metals to lubricate the mold metal interface which compriseslubricating amount of a mineral oil of lubricating viscosity having acarbon residue below about 0.1 percent (Ramsbottom) and an aromaticcarbon content less than about 1 percent and from about 2 to 15 weightpercent of total dimer and trimer of an unsaturated fatty acid of aboutl0 to 20 carbon atoms, sufficient trimer acid being present to giveinsolubles, and a giyceride oil in amount sufficient to solubilize thetrimeric unsaturated acid in the mineral oil.

2. The composition of claim 1 in which the glyceride oil is present inamount up to at least about 30 weight percent of said lubricatingcomposition.

3. The composition of claim 2 in which the dimer and trimer unsaturatedfatty acid is an acid of 18 carbon atoms.

4. The composition of claim 1 wherein the total dimer and trimer of anunsaturated fatty acid is present in amount of about 3 to weight percentof said lubricating composition.

5. The composition of claim 1 wherein the mineral oil of lubricatingviscosity has a viscosity of at least about 100 S.U.S. at 100 F. andcontains at least about 60 percent paraffinic carbon atoms.

6. The composition of claim 1 wherein the mineral oil of lubricatingviscosity is prepared by hydrogenating a distillate mineral lubricatingoil feedstock in a dual catalytic stage system, the first stage of whichemploys a sulfur-resistant hydrogenation catalyst at temperatures ofabout 600 to 750 F., and the second stage of which employs a platinumgroup metal catalyst at temperatures of about 450 to 700 F.

7. The composition of claim 3 wherein the mineral oil of lubricatingviscosity is prepared by hydrogenating a distillate mineral lubricatingoil feedstock in a dual catalytic stage system, the first stage of whichemploys a sulfur-resistant hydrogenation catalyst at temperatures ofabout 600 to 750 F. and the second stage of which employs a platinumgroup metal catalyst at temperatures of about 450 to 700 F.

8. The composition of claim 7 wherein the first stage catalyst hasnickel or cobalt and molybdenum supported on alumina and the secondstage catalyst is platinum-alumina.

9. A method of lubricating the metal-mold interface in the continuouscasting of metals process which comprises providing a lubricatingcomposition of claim 1 to said metal-mold interface.

10. A method of lubricating the metal-mold interface in the continuouscasting of metals process which comprises providing a lubricatingcomposition of claim 3 to said metal-mold interface.

11. A method of lubricating the metal-mold interface in the continuouscasting of metals process which comprises providing a lubricatingcomposition of claim 4 to said metal-mold interface.

12. A method of lubricating the metal-mold interface in the continuouscasting of metals process which comprises providing a lubricatingcomposition of claim 8 to said metal-mold interface.

13. The method of claim 9 in which the metal is steel.

14. The method of claim 10 in which the metal is steel.

15. The method of claim 11 in which the metal is steel.

16. The method of claim 12 in which the metal is steel.

2. The composition of claim 1 in which the glyceride oil is present inamount up to at least about 30 weight percent of said lubricatingcomposition.
 3. The composition of claim 2 in which the dimer and trimerunsaturated fatty acid is an acid of 18 carbon atoms.
 4. The compositionof claim 1 wherein the total dimer and trimer of an unsaturated fattyacid is present in amount of about 3 to 10 weight percent of saidlubricating composition.
 5. The composition of claim 1 wherein themineral oil of lubricating viscosity has a viscosity of at least about100 S.U.S. at 100* F. and contains at least about 60 percent paraffiniccarbon atoms.
 6. The composition of claim 1 wherein the mineral oil oflubricating viscosity is prepared by hydrogenating a distillate minerallubricating oil feedstock in a dual catalytic stage system, the firststage of which employs a sulfur-resistant hydrogenation catalyst attemperatures of about 600* to 750* F., and the second stage of whichemploys a platinum group metal catalyst at temperatures of about 450* to700* F.
 7. The composition of claim 3 wherein the mineral oil oflubricating viscosity is prepared by hydrogenating a distillate minerallubricating oil feedstock in a dual catalytic stage system, the firststage of which employs a sulfur-resistant hydrogenation catalyst attemperatures of about 600* to 750* F. and the second stage of whichemploys a platinum group metal catalyst at temperatures of about 450* to700* F.
 8. The composition of claim 7 wherein the first stage catalysthas nickel or cobalt and molybdenum supported on alumina and the secondstage catalyst is platinum-alumina.
 9. A method of lubricating themetal-mold interface in the continuous casting of metals process whichcomprises providing a lubricating composition of claim 1 to saidmetal-mold interface.
 10. A method of lubricating the metal-moldinterface in the continuous casting of metals process which comprisesproviding a lubricating composition of claim 3 to said metal-moldinterface.
 11. A method of lubricating the metal-mold interface in thecontinuous casting of metals process which comprises providing alubricating composition of claim 4 to said metal-mold interface.
 12. Amethod of lubricating the metal-mold interface in the continuous castingof metals process which comprises providing a lubricating composition ofclaim 8 to said metal-mold interface.
 13. The method of claim 9 in whichthe metal is steel.
 14. The method of claim 10 in which the metal issteel.
 15. The method of claim 11 in which the metal is steel.
 16. Themethod of claim 12 in which the metal is steel.